Mechanical overlay



Patented 9, 1941 to Graphic a r N. .L, a corporation of New Jersey em flm a No Drawing Application W. 11,1938. 1 a SerialNo.246,&97-

. (own-+255)" This invention relates to a mechanical overlay, useful in the printing of halftone cuts, such as are useful in relief printing, and is particularly useful for the purpose of providing reproductions showing an increase in contrast between the shades and highlights of a photoengravers cut, halftone plates and generally similar means of printing.

Heretofore, there have been in, use several mechanical overlay devices, for example, zinc overlay, chalk overlay, powder overlay, hand out overlay, and also spot overlay or sheets. The desired relief for an overlay is produced in the case of the powder overlay by dusting the print with various kinds of powder, more of same adhering to the heavy layer of ink in the shadows and less to the middle tones and highlights. When a powdered resin is applied which will melt and swell under heat, a relief is produced thereby. The so-called chalk overlay consists of a sheet coated with a chalk compound. An impression is made by means of a special ink on the coated surface and the portions not covered by the inked impression are dissolved or etched out in a solution of chlorinated lime. The objectionable features of this process are the use of chemicals, the skill and care required in developing the relief, the slow drying, the expansion of the sheet on absorbing water and shrinking on drying, making register uncertain, furthermore, the limited resistance of the overlay relief to the pressure to which it necessarily is subjected in the printing press.

The present invention aims to provide an overlay (or underlay) that will neither stretch nor shrink, thus insuring perfect register, that is developed, without chemicals, in water, which dissolves out the portions not covered by the impression, together with the highlights, leaving a hard, pliable, relief that will withstand the pressure and pounding to which it is exposed, for instance, on a newspaper rotary press.

The invention applies also to the so-called embossing process in printing, printing, as this invention admits of the production of male and corresponding female reliefs.

i. e., raised letter This is accomplished by making an impression from the same cut or compos'tion on the overlay sheetyone impression made with the special ink to be used in connection with the invention, the second impression made'with an ink soluble in any solvent in which the special overlay ink (serving as a water resisting etch-ground) is insoluble, as, for example,"a glycerine The latter sheet is then covered, in any convenient way, with the special overlaylnkor any pound similar in properties and reaction with the sheet coating, but repelled by the substances con stituting the ink for the female relief, whereupon the impression is removed and the overlay coating dissolved out in water. The first impression supplies the male, the second impression the female die.

In carrying out the invention, a support is prepared'by water-proofing a suitable paper, for instance, or bysupplying a waterproof base, and coating same by means of well-known coating processes, with a colloidal compound, soluble or made soluble in water, in a'predetermined thickness. Among other substances that could be made to serve may be mentioned here such as gelatine, casein, natural or synthetic gums or resins. The inkto be used for the impressions serves as an etch-ground and is insoluble in and impermeable towater and alcohol. It may also be made, in correspondence with the properties and solubility of the overlay compound, chemically reactive with same so as to combine with the overlay compound or affect it chemically and form, a hard, smooth surface. For instance, the ink may act as an acid reagent in neutralizing an overlay compound soluble in waterin its alkaline state and insoluble therein in neutral or acid condition, and/or as an oxidant, and/or in combination with a metal salt, e. g., Cu, Fe, Cr, Sn, and/or insolubilize by photolysis, and/or several reactions eifected simultaneously.

Essentially one aspect of my process involves the application to an overlay sheet of an appropriate colloidal compound, normally insoluble in water, but rendered soluble by chemical treatment; next the application to the said coating of specially prepared inks so that the area of the coating affected by the inks are insoluble in. water, leaving the unaffected parts still soluble so that the overlay paper when washed in water will have areas in relief in proportion to the areas afiected by the special ink treatment. Naturally, it would be possible to alter my invention so that the washings could be in solutions other than water. Also, the thickness of the coating will vary under practical operating conditions, coatings of from three to 'five thousandths of an inch being adapted to provide the ordinary requirements in overlay paper. 7 I

I now giv a number of illustrations [of practical products and processes,

. Z ve i1 ,1 H,- fo h i i by ink of an alkalinized colloidal compound? A paper support may coated with a coun 'arone solution, for w i rvrw'fl s-i d u n hwaterproofed'paper is applied. a coating of alkalinlsed. colloidal compoimd consisting of, by

weight, casein 150 parts, ethanolamine 15 parts, alcohol 100 when water 650 parts, trithe coating is hardened. the coated pap r maybe printed upon with special ink, adapted to. render the coating insoluble in water, such ink consisting of, by weight, asphaltum 40%, cede oil 50%,

acetic acid 10%. The acid/should be present in proportion at least sufllcient to neutralize the alkalinized colloidal coating, thereby returning it to its original water soluble state. In place of acetic acid, various other acids, with or without alcohol to cause the same to be miscible with the remaining constituents of the formula, could be utilized, for example, formic, propionic, tartaric,

citric.'hydrochloric acids. This process, as de-.

addition to casein, are gelatine and particularly organic resins, such as shellac.

Example 2,-Inks oxidizing casein gelatine and organic resins: The alkaline "colloidal compound described in Example 1 may be rendered insoluble by oxidation by an ink of the following formula: Colophony 37 Cade oil 37 isopropyl ether 5%, formaldehyde butyl alcohol 5%.

Example 3.-This formula is illustrative of the insolubilizing action of light upon organic resins, such as shellac, casein or gelatine. Alkaline colloidal compound, such as described in Example 1, may be used. The ink may comprise glycerin 70, gum Arabic 50, water 150 and ammonium dichromate 9, approximate parts by weight. Coatings of the nature described may therefore be rendered insoluble by the action of light, when properly inked, and such coatings are within the purview of my invention.

Example 4.Formation of insoluble metallic resinates: Insoluble metallic resinates may be formed by inks adapted to form such compounds with resinous coatings, for example, an ink as follows: Glycerin 70, soluble starch 20, ferric chloride 10, dextrin 70, water 100, approximate parts by weight, may be used to ink in selected portions a coating formed in the following proportions: Shellac 35%, gum gamboge water 20%, methyl alcohol 20%, ethanolamine 5%. Other organic salts will suggest themselves to those skilled in the arts. Such salts could, of course, contain copper, tin, etc., and also it is possible to use certain metallic salts in connection with casein overlay coatings to render the same insoluble.

Example 5.Surface protection for soluble colloids: A soluble colloidal compound such as described in Example ,1 may be applied to paper and desired relief areas obtained thereon by virtue of applying well-known greasy inks, thus protecting greasy inked areas from the solvent action of water. .In this example there is no chemical action upon the colloidal coating, the greasy ink, or other application, of similar nature, serving but to give the soluble colloidal compound an insoluble protective surface coating, preferably impervious to water.

Example '6.-Combined reversal of pH and oxidation: A coating such as described in connection with Example 1 may be printed upon where relief 500, water 1500, acetic tective covering shellac 35%,

areaa'are desired, with the following ink ofalycerin type, comprising glycerin700, gum Arabic acid 100, formaldehyde 65. and, as thickener. dextrin .300 parts, by weight.

Example 7.Combined reversal of pH and proof ink: An overlay coating oi gum gamboge 20%, water 20%. methyl alcohol 20%, ethanolamine 5%, by weight. may be prepared, and an ink comprising asphaltum Cade oil 28%, dipentine 5%, spike oil 5%, dioxan 7.6%, acetic acid 14%, copper acetate 2%, octyl alcohol 6.4%, butyl alcohol 2%. Such water insoluble ink will ordinarily form a satisfactory etch-ground, but the pH reversal is very desirable to prevent the under cutting of the ink areas, especially in the middle tones of the halftone'impl'ession, and this purpose is served very satisfactorily by the indicated acid reaction of the inking compound.

.If desired as merely a water insoluble ink, the acetic acid, copper acetate and alcohols may be omitted from the above formula.

Among other advantages it will be recognized that one novel feature of my invention is the use of water only as an etchingsolution. Also, my

.improved mechanical overlays are'strong and protein is insoluble at a tough and are resistant to the high pressures and strains and stresses involved in printing processes. It will be noted that relief areas by my invention involving the various colloids described, and particularly the various organic resins, may be provided by inks, or other media, affording a protective covering only, b a protective covering plug a chemical reaction, c a chemical reaction only.

Also, it will be noted that I may produze male and female reliefs for embossing purposes by dissolving out portions left exposed by an impressionwith a special overlay ink for the male die, and by making a corresponding female die in two steps, namely, first by placing a printing impression upon the coating with a chemically inert water soluble ink, and then' next covering the non-inked portions with a special overlay ink or compounds of a similar nature and removing the inert ink and then dissolving out the portions then exposed.

From the above description it will be noted that fundamentally my invention may be said to relate particularly to a water soluble preferably smooth, strong, flexible, homogeneous layer of material upon a backing and adapted to be rendered insoluble in predetermined areas by l a change of hydrogen ion, for example, soya bean pH of 4.6, but is soluble at a pH of 6 or 8. 2 oxidation, 3 reduction, 4 photolysis, 5 polymerization, 6 mechanical protection aiforded by water impervious inks, and 7 metathesis. It is obvious that the same relief impression member used in printing may be used to print on an ink, or other substance used to effect the soluble coating or layer upon the mechanical overlay. It is also obvious that combinations 01' the various factors named above may be utilized. It is also obvious that normally insoluble materials may be converted to soluble materials when placed upon the overlay material, and then certain relief areas made insoluble by the chemical actions of inks, or other media. It is also obvious that various coating or layering substances, such as hereinbefore described, may be utilized and that any strong, tough, tenacious, homogeneous and flexible coating or layering material formed from various resins or colloidal materials, with or without plasticizers, may be utilized.

2,205,974 The inks and coatings described hereinbefore' material, and the shadows remain substantially the same, when washed with water.

Various modifications and combinations of various features of the present invention as heretofore set out by illustrative examples will now occur to those skilled in the art from this description and the examples given above, and certain procedures described may b replaced by other procedures and certain features used without other features, without departing from the spirit of the invention. Reference is therefore to be had to the claims for a definition of my invention. I

Having described my invention, I claim:

1. A method of providing mechanical overlay which involves etching by water solutions alone including the steps of coating a backing material with a water soluble coating, protecting certain areas of said water soluble colloidal coating with solutions applied directly by the printing means so that the same are relatively insoluble, washing the said coating material in water, thus washing away the unprotected soluble areas of the coating and leaving certain insoluble areas in relief.

2. A method of providing mechanical overlay which involves etching by water solutions alone,

lected and predetermined areas of said film are mechanically protected by water impervious inks or the like.

6. The method defined in claim 2 wherein predetermined areas of said soluble coating are rendered insoluble by inks chemically reactive thereon and applied by an impression member.

7. The method of producing a mechanical overlay for printing means which includes utiwhich includes the steps of coating a water resistant backing material with a smooth homogeneous tenacious layer of water soluble colloid film, covering predetermined areas of said film with a protective layer applied directly by the printing means adapted to prevent the water solution of said predetermined areas, washing the backing material in water thus washing away the unprotected soluble areas of the layer and leaving the protected areas in relief.

3. The method defined in claim 2 wherein said colloid is normally insoluble but is rendered water soluble by alkaline treatment, and wherein the protective coating applied in predetermined areas thereon comprises an acidifying ink.

4. The method defined in claim 2 wherein said water soluble colloid is rendered insoluble in predetermined areas by pH control.

5. Th method defined in claim 2 wherein seing chemically with said water soluble material to lizing the printing means by applying an insolubilizing substance directly by the printing means to a suitable water-soluble colloidal layer of material upon a backing sheet and then washing away the soluble portions of said layer.

8. As an article of manufacture, a mechanical overlay sheet including in combination, a layer of pliable water resistant paper, a coating carried 1 by said paper formed of tough water resistant,

soluble material and adapted to be printed upondirectly by printing means in predetermined areas with an ink-like substance, the latter uniting chemically with said water soluble material to render the same insoluble.

9. As an article of manufacture, a mechanical overlay sheet including in combination, a layer of pliable water resistant paper, a coating carried by said paper formed of a tough water soluble, colloidal film and adapted to be printed upon directly by printing means in predetermined areas with an ink-like substance, the latter uniting chemically with said water soluble material to render the same insoluble.

10. As an article of manufacture, a mechanical overlay sheet including in combination, a layerof pliable water resistant paper, a coating carried by said paper formed of tough, water. soluble,

areas with an ink-like substance, the latter uniting chemically with said water soluble material to render the same insoluble.

11. As an article of manufacture, a'mechanical overlay sheet including in combination, a layer of pliable water resistant paper, a coating carried by said paper formed of tough, watersoluble, v

colloidal, resinous film and adapted to be printed upon directly by printing means in predetermined areas with an ink-like substance, the latter unitrender the same insoluble.

WILLIAM HEINECKE. 

